As-salamu `alaykum, sister.
The answer to your question depends on what you have decided to do work and leave your baby in daycare or with grandparents. If you leave your baby with grandparents, then make sure that they can cope with the 1-year-old, who requires lots of attention. Grandparents are a better choice than day care.
If the child stays with you, you can pick up your son after work and this way the baby does not completely forget you and the father.
Children from 1 to 5 (the formative years) establish close bonds with the primary caregivers, namely mothers, and often take the time to attach to secondary caregivers, even mothers. If you decide to send your child to live with his grandparents in India, then you must be fully prepared for this: that when he returns in the beginning, he may not emotionally respond to you as he would to his grandparents.
As to the long-term impact, it is hard to predict. Every child is unique and has different needs, but if he is in a loving environment he should be able to transfer his affection to you and your husband over a period of time, provided you bring your parents along for the smooth transfer.
It is always a hard decision for parents of very small children, especially mothers, so may Allah guide you.
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